Permanent Dipole Moment

Permanent dipole moment refers to the separation of electrical charges within a molecule due to differences in electronegativity between atoms and the molecule's molecular geometry.

Factors Affecting Permanent Dipole Moment

The factors affecting permanent dipole moment include:

1. Electronegativity Difference: The greater the electronegativity difference between atoms, the stronger the dipole moment.

2. Molecular Geometry: The shape of the molecule plays a role in determining the dipole moment. For example, if the molecule is symmetrical, then the dipole moments will cancel out, resulting in a non-polar molecule.

3. Bond Polarity: If the bond is polar, then the molecule will have a permanent dipole moment.

Molecules with Permanent Dipole Moment

1. SiF4: This molecule has a symmetrical tetrahedral shape, and all four fluorine atoms are equally electronegative, resulting in a non-polar molecule.

2. SF4: This molecule has a trigonal bipyramidal shape, with a lone pair of electrons on the sulfur atom. The bond between sulfur and fluorine is polar, and the lone pair of electrons results in a non-symmetrical molecule, giving it a permanent dipole moment.

3. XeF4: This molecule has an octahedral shape, with four fluorine atoms and two lone pairs of electrons on the xenon atom. The bond between xenon and fluorine is polar, and the molecule is non-symmetrical, giving it a permanent dipole moment.

4. BF3: This molecule has a trigonal planar shape, with three fluorine atoms and a boron atom. The bond between boron and fluorine is polar, but the molecule is symmetrical, resulting in a non-polar molecule.

Conclusion

Permanent dipole moment is an important concept in determining the polarity of a molecule. The factors affecting the dipole moment include electronegativity difference, molecular geometry, and bond polarity. Some molecules with a permanent dipole moment include SF4 and XeF4, while others like SiF4 and BF3 are non-polar.

2...SF4 will have permanent dipole moment as no lone pair can cancel dipole b/w S and F atoms